Hardware setup
| HC-SR04 | Raspberry Pi Pico |
|---|---|
| VCC | VSYS |
| GND | GND |
| Trig | GP2 |
| ECHO | GP3 |
I am using raspberry pi model 3 b+ for the code compilation.
- Create the folder named “distance” inside the pico folder
- Then Create the test.c and CMakeLists.txt files using touch command.
touch test.c CMakeLists.txt
- Copy the pico_sdk_import.cmake file from pico/pico-sdk/external
- make the build directory using mkdir command
mkdir build- Here is the CMakeLists.txt code
# Set the minimum required version of CMake
cmake_minimum_required(VERSION 3.13)
# Import the Pico SDK CMake configuration file
include(pico_sdk_import.cmake)
# Set the project name and languages
project(test_project C CXX ASM)
# Set the C and C++ language standards
set(CMAKE_C_STANDARD 11)
set(CMAKE_CXX_STANDARD 17)
# Initialize the Pico SDK
pico_sdk_init()
# Create an executable target called "test" from the source file "test.c"
add_executable(test
test.c
)
# Enable USB stdio for the "test" target (used for serial communication)
pico_enable_stdio_usb(test 1)
# Disable UART stdio for the "test" target
pico_enable_stdio_uart(test 0)
# Add extra outputs for the "test" target (e.g., UF2 file)
pico_add_extra_outputs(test)
# Link the "test" target with the pico_stdlib library
target_link_libraries(test pico_stdlib)
- Here is the c code that you put inside the test.c file
#include <stdio.h>
#include "pico/stdlib.h"
#include "hardware/gpio.h"
#include "hardware/timer.h"
#define TRIG_PIN 2
#define ECHO_PIN 3
float measure_distance() {
gpio_put(TRIG_PIN, 1);
sleep_us(10);
gpio_put(TRIG_PIN, 0);
uint32_t start_ticks = 0;
uint32_t end_ticks = 0;
while (gpio_get(ECHO_PIN) == 0) {
start_ticks = time_us_32();
}
while (gpio_get(ECHO_PIN) == 1) {
end_ticks = time_us_32();
}
uint32_t elapsed_time_us = end_ticks - start_ticks;
float distance_cm = elapsed_time_us * 0.0343 / 2;
return distance_cm;
}
int main() {
stdio_init_all();
sleep_ms(2000); // Wait for sensor to stabilize
gpio_init(TRIG_PIN);
gpio_set_dir(TRIG_PIN, GPIO_OUT);
gpio_init(ECHO_PIN);
gpio_set_dir(ECHO_PIN, GPIO_IN);
while (1) {
float distance = measure_distance();
printf("Distance: %.2f cm\n", distance);
sleep_ms(1000);
}
return 0;
}
- after this you need to execute this line of code in the terminal
export PICO_SDK_PATH=../../pico
- then execute the following code in the given order
cd buildcmake ..
make
If everything worked, you will have your ulf2 file in your build directory
